JP7337059B2 - Protecting components of digital printing systems - Google Patents

Description

CROSS REFERENCE TO RELATED APPLICATIONS This patent application claims the benefit of US Provisional Patent Application No. 62591847, filed November 29, 2017, which is incorporated herein by reference in its entirety.

The present invention relates to systems and methods for protecting elements of a digital printing system from potential damage from foreign objects carried by moving parts of the printing system. Specifically, the present invention is suitable for protecting components of indirect printing systems that use intermediate transfer members.

Various printing devices have previously been proposed that use an indirect inkjet printing process, in which an inkjet printhead is used to print an image onto the surface of an intermediate transfer member, followed by an intermediate transfer. The process by which the member is used to transfer the image to the substrate. The intermediate transfer member (ITM) can be a rigid drum or a flexible belt, also called a blanket (eg, guided over rollers or attached to a rigid drum). Contaminants can be misdirected by the ITM at high speed toward the inkjet printhead, which can damage the printhead if not avoided.

The present disclosure relates to a printing system, such as a flexible intermediate transfer member (ITM) (e.g., blanket) mounted, for example, on multiple rollers (e.g., belt) or via a rigid drum (e.g., drum-mounted blanket). ) and a method of operating a digital printing system with a moving ITM.

An ink image is formed (e.g., by droplet deposition at an imaging station) on the surface of a moving ITM and then transferred to a substrate, which may be paper, plastic, metal, or any other suitable material. can include materials. To transfer the ink image to the substrate, the substrate is pressed between at least one impression cylinder and an area of the moving ITM where the ink image is placed, at which time a transfer station (also called a print station) , is said to be engaged.

For flexible ITMs mounted on multiple rollers, the print station typically includes, in addition to the impression cylinder, a pressure cylinder or roller whose outer surface may optionally be compressible. A flexible blanket or belt passes between two such cylinders, which can be selectively engaged or disengaged, usually when the distance between the two is increased or decreased. One of the two cylinders may be at a fixed position in space, while the other cylinder is moved towards or away from it (e.g. the pressure cylinder is movable or the impression cylinder is movable), or the two cylinders can move toward or away from each other. For rigid ITMs, the drum (on which a blanket can optionally be mounted) constitutes a secondary cylinder that engages and disengages the impression cylinder.

For the sake of clarity, the word rotation is used herein irrespective of whether the movement is locally linear, locally rotated, or otherwise shaped at various locations within the printing press. , is used to represent the movement of the ITM within the printing press in the printing direction. For a rigid ITM with a drum shape or drum support, the motion of the ITM is rotational. The print direction is defined by the movement of the ink image from the imaging station to the printing station. Unless the context clearly indicates otherwise, the terms upstream and downstream that may be used below relate to positions relative to the printing direction.

Some embodiments include a printing system, specifically an intermediate transfer member (ITM) comprising a flexible endless belt mounted on a plurality of guide rollers, and a print bar positioned over the surface of the ITM. wherein the print bar is configured to form ink images on the surface of the ITM by droplet deposition; and a print station where the ink images are transferred to the substrate. A conveyor that drives the rotation of the ITM at a fixed rotational speed in the print direction to transport it toward and the rotating ITM detects foreign objects that are transported upstream of the imaging station to a detection position downstream of the printing station. and operable to the detection system to respond to detection of a foreign object by performing at least one anti-collision action to prevent potential collision between the foreign object and the printbar. and a response system coupled to a printing system.

In embodiments, a printing system includes an intermediate transfer member (ITM) comprising a flexible endless belt mounted on a plurality of guide rollers and an imaging station comprising a print bar positioned over the surface of the ITM. wherein the print bar transports the ink images towards an imaging station configured to form an ink image on the surface of the ITM by droplet deposition and a printing station where they are transferred to the substrate a conveyor for driving the rotation of the ITM at a fixed rotational speed in the printing direction for detection of foreign objects transported by the rotating ITM to a detection position downstream of the printing station upstream of the imaging station; collision prediction circuitry for predicting a potential collision and/or likelihood of a potential collision between a foreign object and a printbar; and a detection system for preventing a potential collision between a foreign object and a printbar. and a response system operably coupled to the prediction circuitry for responding to the prediction of a potential collision by performing at least one anti-collision action.

In some embodiments, a printing system includes an intermediate transfer member (ITM) comprising a flexible endless belt mounted on a plurality of guide rollers and an image comprising a print bar positioned over the surface of the ITM. an imaging station, wherein the print bar is configured to form an ink image on the surface of the ITM by droplet deposition; and an ink image toward a printing station where they are transferred to the substrate. A conveyor for driving the rotation of the ITM at a fixed rotational speed in the print direction for transport and a machine detection system for detecting material conveyed by the rotating ITM at a detection position upstream of the imaging station and downstream of the printing station. wherein the mechanical detection system comprises a linking element (the linking element stiffens the blade) that includes one of an elongated blade longitudinally positioned across the width of the ITM and a tension spring and a pneumatic piston. frame) and at least one of a limit switch and a camera, and the gap G2 between the ITM and the edge of the blade adjacent the ITM is smaller than the gap G1 between the printbar and the ITM. , at the detection position, the ITM detects foreign objects by performing at least one anti-collision action to prevent potential collisions between the machine detection system, which is extended over upstream guide rollers, and the print bar. and a response system operably coupled to the detection system for responding to the detection of.

In embodiments, the printing system includes an intermediate transfer member (ITM) comprising a flexible endless belt mounted on a plurality of guide rollers and a minimum gap of G1 therebetween over the surface of the ITM. an imaging station including a print bar arranged in a row, the print bar configured to form an ink image on the surface of the ITM by droplet deposition; A conveyor driving the rotation of the ITM at a fixed rotational speed in the print direction for transporting it to the printing station where it is transferred to the printing station upstream of the imaging station and into a detection position downstream of the printing station by the rotating ITM. A detection system configured to detect a transported foreign object and respond to detection of the foreign object by performing anti-collision actions within a response time to prevent potential collision between the foreign object and the printbar. a responsive system operatively coupled to the detection system for the purpose, the anti-collision action may include lifting the print bar to a height of at least twice the gap G1, the responsive system electrically An actuator may be included and the response time may be defined by the speed of the rotating ITM and the distance from the detection position to the imaging station along the path of travel of the ITM in the print direction. In some embodiments, the anti-collision action can include lifting the printbar to a height that is at least five times the gap G1. In some embodiments, the anti-collision action can include lifting the printbar to a height that is at least ten times the gap G1.

In embodiments, a printing system includes an intermediate transfer member (ITM) comprising a flexible endless belt mounted on a plurality of guide rollers and an imaging station comprising a print bar positioned over the surface of the ITM. wherein the print bar transports the ink images towards an imaging station configured to form an ink image on the surface of the ITM by droplet deposition and a printing station where they are transferred to the substrate a conveyor for driving the rotation of the ITM at a fixed rotational speed in the print direction for the purpose of printing; The machine detection system consists of an elongated blade longitudinally positioned across the width of the ITM and a linking element (linking element links the blade to a rigid frame) that includes one of a tension spring and a pneumatic piston. and at least one of a limit switch and a camera, the gap G2 between the ITM and the edge of the blade adjacent the ITM is less than the gap G1 between the printbar and the ITM, and the detection position , the ITM detects foreign objects by performing anti-collision actions within a response time to prevent potential collisions between the machine detection system and the print bar, which are stretched over the upstream guide rollers. and a response system operatively coupled to the detection system for responding to the anti-collision action, the response system may include an electrical actuator, and the response time may be defined by the speed of the rotating ITM and the distance from the sensing position to the imaging station along the path of travel of the ITM in the print direction. In some embodiments, the anti-collision action can include lifting the printbar to a height that is at least five times the gap G1. In some embodiments, the anti-collision action can include lifting the printbar to a height that is at least ten times the gap G1.

In some embodiments, the detection system can include one of a laser transmitter, an image processing system, an acoustic detection system, and a mechanical detection system. In some embodiments, the detection system can include a detection element positioned adjacent the ITM at the detection location and oriented in the cross-print direction. The detection elements can include one of laser beams, musical strings, and elongated blades.

In some embodiments, the gap G2 between the sensing element and the ITM can be smaller than the gap G1 between the printbar and the ITM. Gap G2 may be no more than 90% of gap G1. In some embodiments, gap G2 may be no more than 70% of gap G1. In some embodiments, gap G2 may be no more than 70% of gap G1.

In embodiments, at the detection position, the ITM is stretched over the upstream guide rollers. A printing system can define an x-axis, a y-axis, and a z-axis, where the x-axis and z-axis are parallel to the floor, orthogonal to each other, together define a plane, and the y-axis is orthogonal to its plane and tangential to the ITM at the detection position in the print direction has only the y-axis dimension, the detection element has at least the z-axis dimension, and the gap G2 has only the x-axis dimension. . The distance from the sensing position to the imaging station along the path of travel of the ITM in the print direction can be less than 10% of the total length of the ITM. This distance can be less than 5% of the total length of the ITM. This distance can be less than 2% of the total length of the ITM. In embodiments, the fixed rotational speed can be between 1/10 and 1/2 revolutions per second. In some embodiments, the fixed rotational speed can be between 1/8 and 1/4 revolutions per second.

A detection system according to embodiments can include a geometric detection system configured to detect an impact between a detection element and a foreign object. In embodiments, the detection system and the response system are configured such that execution of at least one anti-collision action is conditional on the strength of the impact between the foreign object and the detection element exceeding a predetermined threshold. obtain. The detection system and response system are configured such that execution of at least one anti-collision action is contingent upon a computed prediction of the strength of a future collision between the foreign object and the printhead exceeding a predetermined threshold. can be configured to be

In embodiments, the at least one anti-collision action includes lifting the printbar. The print bar lift can be to a height of at least 2 times or at least 5 times or at least 10 times the gap G1. In some embodiments, the print bar lift can be to a height of at least five times the gap G1. In some embodiments, the lift of the printbar can be to a height of at least ten times the gap G1.

According to embodiments, the contaminants include transparent treatment coatings applied to the surface of the ITM downstream of the printing station and upstream of the detection location, silicon-containing materials contained in the surface release layer of the ITM, dried ink, substrate material, At least one of a cleaning solution and a cooling solution may be included.

In some embodiments, at least one preventive action may include moving the surrogate to a position upstream of the printbar so that the foreign object hits the surrogate instead of the printbar. In some embodiments, the response time for prevention of potential collisions between the foreign object and the print bar depends on the speed of the rotating ITM and the detection position along the path of travel of the ITM in the print direction to the imaging station. and the detection system and the response system may be configured to cause at least one anti-collision action to be performed within the response time. The response time can be less than 1 second. Response time can be less than 500 milliseconds. Response time can be less than 200 milliseconds. In some embodiments, the at least one anti-collision action can further include stopping rotation of the ITM.

According to embodiments of the present invention, a rotating intermediate transfer member ( A mechanical detection system for detecting foreign objects carried by an ITM) includes at least one of an elongated blade, linkage means including a spring (the linkage means links the blade to a rigid frame), limit switches and a camera. can contain one.

In some embodiments, by a rotating intermediate transfer member (ITM) within a printing system (including an imaging station where the ink image is formed on the ITM and a printing station where the ink image is transferred to the substrate). A mechanical detection system for detecting conveyed foreign objects may include an elongated blade, a spring connecting the blade to a rigid frame, and at least one of a limit switch and a camera.

In some embodiments, by a rotating intermediate transfer member (ITM) within a printing system (including an imaging station where the ink image is formed on the ITM and a printing station where the ink image is transferred to the substrate). A mechanical detection system for detecting conveyed foreign objects may include an elongated blade, a resilient intervening element connecting the blade to a rigid frame, and at least one of a limit switch and a camera.

In embodiments, the machine detection system may be located downstream of the printing station and upstream of the imaging station at a detection location facing the ITM. The edge of the elongated blade proximate to the ITM may be positioned with a gap therefrom such that foreign particles larger than the gap in a direction perpendicular to the surface of the ITM at the detection location impact the edge of the elongated blade. become. A mechanical detection system may be configured to detect an impact between the foreign object and the elongated blade. Detecting may include at least one of contacting a limit switch and determining the angle of the blade from the image. The machine detection system may be further configured to signal the response system to initiate an anti-collision response to prevent collisions between the foreign object and components of the imaging station. Signaling the response system may be conditioned on the intensity of the impact between the foreign object and the elongated blade exceeding a predetermined threshold. In some embodiments, the machine detection system can further include a pivot.

Some embodiments include a printing system, specifically a print bar, which forms ink images on a rotating intermediate transfer member (ITM) and the ink images are transferred to a printing station where they are transferred to a substrate. a method of operating a printing system subsequently transported by a , the method comprising detecting a foreign object transported by a rotating ITM at a detection position upstream of an imaging station and downstream of a printing station; and responding to the detection by performing at least one anti-collision action to prevent a potential collision with the bar. Detection can be accomplished by using a detection system that includes one of a laser transmitter, an image processing system, an acoustic detection system, and a mechanical detection system. Detecting can be accomplished by using a detection system that includes a detection element positioned adjacent to the ITM at the detection location and oriented in the cross-print direction. The detection elements can include one of laser beams, musical strings, and elongated blades.

In embodiments of this method, the gap G2 between the sensing element and the ITM can be smaller than the gap G1 between the printbar and the ITM. Gap G2 may be no more than 90% of gap G1. In some embodiments, gap G2 may be no more than 70% of gap G1. In some embodiments, gap G2 may be no more than 70% of gap G1. In embodiments of this method, the ITM may be stretched on guide rollers upstream of the detection location.

According to some embodiments of the method, the printing system defines x-, y-, and z-axes, where the x- and z-axes are parallel to the floor and orthogonal to each other; A vector which together defines a plane, the y-axis being orthogonal to that plane and tangent to the ITM at the detection position in the print direction, has only the y-axis dimension, the detection element has at least the z-axis dimension, and the gap G2 has only the x-axis dimension.

In embodiments of this method, the distance from the sensing position to the imaging station along the path of travel of the ITM in the print direction may be less than 10% of the total length of the ITM. The distance can be less than 5% of the total length of the ITM. The distance can be less than 2% of the total length of the ITM. The fixed rotational speed can be between 1/10 revolutions per second and 1/2 revolutions per second. In some embodiments, the fixed rotational speed can be between 1/8 revolution per second and 1/4 revolution per second.

In some embodiments, detecting can be accomplished using a mechanical detection system configured to detect an impact between the sensing element and the foreign object. In some embodiments, a response to detection can be conditioned on the strength of the impact between the foreign object and the sensing element exceeding a predetermined threshold. In some embodiments, the response to detection may be contingent upon a computed prediction of the strength of a future collision between the foreign object and the printhead exceeding a predetermined threshold.

In embodiments of the method, the at least one anti-collision action may include lifting the printbar. The print bar lift can be to a height of at least twice the gap G1. In some embodiments, the printbar lift can be to a height of at least five times the gap G1. In some embodiments, the printbar lift can be to a height of at least 10 times the gap G1.

In some embodiments of this method, the contaminants include transparent treatment coatings applied to the surface of the ITM downstream of the printing station and upstream of the detection location, silicon-containing materials contained in the surface release layer of the ITM, dried ink, At least one of a substrate material, a cleaning solution, and a cooling solution may be included. In some embodiments of the method, at least one preventive action includes moving the surrogate to a position upstream of the printbar so that the foreign object strikes the surrogate instead of the printbar.

In an embodiment of this method, the response time for prevention of potential collisions between the foreign object and the printbar depends on the speed of the rotating ITM and the detection position along the path of travel of the ITM in the print direction to the imaging station. and the response may be achieved such that at least one anti-collision action is performed within the response time. The response time can be less than 1 second. Response time can be less than 500 milliseconds. Response time can be less than 200 milliseconds.

In some embodiments of the method, the at least one anti-collision action may further include stopping rotation of the ITM.

In embodiments, a printing system includes an intermediate transfer member (ITM) comprising a flexible endless belt mounted on a plurality of guide rollers and an imaging station comprising a print bar positioned over the surface of the ITM. wherein the print bar transports the ink images towards an imaging station configured to form an ink image on the surface of the ITM by droplet deposition and a printing station where they are transferred to the substrate and a machine detection system (machine detection The system includes elongated blades longitudinally positioned across the width of the ITM and linking elements (linking elements linking the blades to a rigid frame) including one of a tension spring and a pneumatic piston. , a limit switch that detects the orientation of the elongated blade, a camera that images the elongated blade, and image circuitry that detects the orientation of the elongated blade by analyzing the output of the camera (the ITM and the edge of the blade proximate to the ITM). is smaller than the gap G1 between the print bar and the ITM, and at the detection position, the ITM is extended over the upstream guide roller); a response system operably coupled to the detection system for responding to detection of a conveyed foreign object by performing at least one anti-collision action to prevent potential collision with the bar.

In embodiments, a printing system includes an intermediate transfer member (ITM) comprising a flexible endless belt mounted on a plurality of guide rollers and an imaging station comprising a print bar positioned over the surface of the ITM. wherein the print bar transports the ink images towards an imaging station configured to form an ink image on the surface of the ITM by droplet deposition and a printing station where they are transferred to the substrate a conveyor for driving the rotation of the ITM at a fixed rotational speed in the printing direction for the purpose of printing; and a machine detection system (machine The detection system consists of elongated blades longitudinally positioned along the width of the ITM and expandable link elements (expandable link elements are resilient and/or have pneumatic or hydraulic based resistance). , a tension spring and a pneumatic piston, the expandable linking element linking the blade to the rigid frame) and at least one blade orientation detector for detecting the orientation of the elongated blade or its rotation. including at least one of a switch and a camera (the gap G2 between the ITM and the edge of the blade adjacent to the ITM is smaller than the gap G1 between the printbar and the ITM, and at the detection position, the ITM extended over an upstream guide roller)) and to respond to detection of a conveyed foreign object by performing at least one anti-collision action to prevent potential collision between the foreign object and the printbar. and a response system operably coupled to the detection system.

In some embodiments, the expandable link element includes a spring. In some embodiments, the expandable linking element includes a pneumatic or hydraulic piston. In some embodiments, the blade orientation detector includes a limit switch that detects the orientation of the blade. In some embodiments, the blade orientation detector includes a camera that images the elongated blade and image circuitry that detects the orientation of the elongated blade by analyzing the output of the camera. In some embodiments, the blade orientation detector is magnetic (using reed switches or proximity switches in non-limiting examples). In some embodiments, the blade orientation includes an encoder;

In embodiments, the printing system includes an intermediate transfer member (ITM) comprising a flexible endless belt mounted on a plurality of guide rollers and a minimum gap of G1 therebetween over the surface of the ITM. an imaging station including a print bar arranged in a row, the print bar configured to form an ink image on the surface of the ITM by droplet deposition; conveyed by the rotating ITM upstream of the imaging station to a detection position downstream of the printing station by a conveyor that drives rotation of the ITM at a fixed rotational speed in the printing direction for transport toward the printing station where it is transferred to the a detection system configured to detect a foreign object being detected and a delivered foreign object detected by lifting the printbar to prevent potential collision between the detected delivered foreign object and the printbar; and a printbar lift system operably coupled to the detection system for responding to detection of.

In some embodiments, the response system includes an electrical actuator. In some embodiments, the lift of the print bar is performed within a response time defined by the speed of the rotating ITM and the distance from the detected position to the imaging station along the path of travel of the ITM in the print direction. be done. In some embodiments, the lift of the printbar is to a height of at least twice the gap G1. In some embodiments, the printbar lift can be to a height of at least five times the gap G1. In some embodiments, the printbar lift can be to a height of at least 10 times the gap G1.

The present invention will now be further described, by way of example, with reference to the accompanying drawings, in which dimensions of components and features shown in the figures are chosen for convenience and clarity of presentation and are not necessarily to scale. isn't it.

1 is an elevational view of a printing system according to embodiments; FIG. 1 is an elevational view showing components of a printing system according to embodiments; FIG. 1 is an elevational view showing components of a printing system according to embodiments; FIG. 1 is a perspective view of an example detection system according to embodiments; FIG. 2A-2C are two alternative elevation views showing components of a detection system according to embodiments; FIG. 2 is an elevational view showing components of a detection system according to embodiments; FIG. 4 is a perspective view of another example of a detection system according to embodiments; 6B are two alternative elevation views showing components of the detection system shown in FIG. 6A; FIG. FIG. 3 is a perspective view of another example of a detection system according to embodiments; FIG. 3 is a perspective view of another example of a detection system according to embodiments; FIG. 3 is a perspective view of another example of a detection system according to embodiments; 8B is two alternative elevation views showing components of the detection system shown in FIG. 8A; FIG. 4 is a flow diagram illustrating a method of operation of a printing press including a detection system according to embodiments; 4 is a flow diagram illustrating a method of operation of a printing press including a detection system according to embodiments; 4 is a flow diagram illustrating a method of operation of a printing press including a detection system according to embodiments; 4 is a flow diagram illustrating a method of operation of a printing press including a detection system according to embodiments; 1 is an elevational view showing components of a printing system including a detection system according to embodiments; FIG. 1 is an elevational view showing components of a printing system including a detection system according to embodiments; FIG. 4 is a flow diagram illustrating a method of operation of a printing press including a detection system according to embodiments; FIG. 2 is an elevational view showing components of a detection system according to embodiments; 1 is an elevational view showing components of a printing system including a detection system according to embodiments; FIG. 17B is a perspective view showing the components of the detection system shown in FIG. 17A; FIG. 1 is an elevational view showing components of a printing system according to embodiments; FIG. 1 is a plan view showing components of a printing system according to embodiments; FIG.

The invention will now be described, by way of example only, with reference to the accompanying drawings. The drawings will now be described with particular detail, although the details shown are by way of example and for purposes of illustrative discussion of the preferred embodiment of the invention only, and the principles and conceptual aspects of the invention most useful. Emphasis is given to provide what is believed to be an explanation that is easily understood in In this regard, no attempt has been made to show structural details of the invention in more detail than is necessary for a basic understanding of the invention, and this description, taken in conjunction with the drawings, is intended to illustrate the various aspects of the invention in practice. It will be clear to those skilled in the art how this can be implemented in Like numbers are generally used throughout the drawings to designate like elements.

For convenience, various terms are presented here in the context of the description herein. To the extent definitions are provided, either explicitly or implicitly, here or elsewhere in this application, such definitions are understood to be consistent with the use of the terms as defined by those skilled in the art. Moreover, such definitions should be interpreted in the broadest possible sense consistent with such usage.

For purposes of this disclosure, "electronic circuitry" is intended to broadly describe any combination of hardware, software, and/or firmware. The electronic circuitry may comprise executable code modules (i.e., stored on a computer-readable medium) and/or Field Programmable Logic Array (FPLA) element(s), hardwired logic element(s). firmware element(s), including but not limited to field programmable gate array (FPGA) element(s), and application specific integrated circuit (ASIC) element(s). or multiple) and/or hardware element(s). Any instruction set architecture may be used including, but not limited to, reduced instruction set computer (RISC) architecture and/or complex instruction set computer (CISC) architecture. The electronic circuitry may be located at a single location or distributed among multiple locations, in the latter case the various circuitry elements are assumed to be in electronic communication with each other, either by wire or wirelessly. can do.

In various embodiments, the ink image is first applied to the surface of an intermediate transfer member (ITM) and transferred from the surface of the intermediate transfer member to the substrate (ie, sheet substrate or web substrate). For purposes of this disclosure, the terms "intermediate transfer member," "image transfer member," and "ITM" are synonymous and may be used interchangeably. The locations where ink is applied to the ITM are referred to as "imaging stations." In many embodiments, ITM includes "belt," "endless belt," or "blanket," and these terms are used interchangeably with ITM.

The section or area of the printing press where the ink image is transferred to the substrate is the "printing station." It should be appreciated that for some printing systems there may be multiple printing stations. In some embodiments of the invention, the intermediate transfer member is formed as a belt including a strength or support layer coated with a release layer. In a non-limiting example, the reinforcing layer can be a woven fabric that is fiber reinforced so that it is substantially inextensible in the length direction. "Substantially inextensible" means that during any cycle of the belt, the distance between any two fixed points on the belt does not change to the extent that image quality is affected. do. However, belt length can change with temperature or over longer periods of time with aging or fatigue. Across its width, the belt can have a low degree of elasticity to help it stay taut and flat as it is pulled through the imaging stations. A suitable fabric may, for example, have longitudinal glass fibers woven, stitched, or otherwise held to perpendicular cotton fibers.

For an endless intermediate transfer member, the "length" of the ITM is defined as its circumference.

Referring now to the drawings, FIG. 1 is a schematic diagram of a printing system 100 for indirect printing according to some embodiments of the present invention. The system of FIG. 1 includes an intermediate transfer member (ITM) 210 comprising a flexible endless belt mounted on a plurality of guide rollers 232,240,250,253,242. In another example (not shown), the ITM 220 is a drum or belt wrapped around a drum. This figure shows aspects of the particular configuration with which the present invention is being discussed, and the illustrated configuration is not limited to the indicated number and arrangement of rollers, nor to their shapes and relative dimensions, all of which are , here for convenience in illustrating the system components in a clear fashion.

In the example of FIG. 1, ITM 210 rotates in a clockwise direction with respect to the figure. The direction of belt travel defines the upstream and downstream directions. Rollers 242 and 240 are positioned upstream and downstream, respectively, of imaging station 212, and thus roller 242 is sometimes referred to as the "upstream roller" and roller 240 is sometimes referred to as the "downstream roller." The printing system 100 further
(a) an imaging station 212 including print bars 222A-222D (each designated as one of C, M Y, and K), each print bar being an inkjet printhead shown in FIG. Imaging station 212 is configured to form an ink image (not shown) on the surface of ITM 210 (eg, by droplet deposition thereon). station 212;
(b) a drying station 214 for drying the ink image;
(c) a printing station 216 where the ink image is transferred from the surface of the ITM 210 to a sheet 231 or web substrate (only the sheet substrate is shown in FIG. 1);
In the specific non-limiting example of FIG. 1, printing station 216 includes impression cylinder 220 and blanket/pressure cylinder 218 carrying compressible blanket 219;
(d) a cleaning station 258 upstream from the printing station (which, as shown in FIG. 1, may include a cleaning brush; this is just one example of cleaning countermeasures that can be used within this system); a cleaning station 258 where residual material (e.g., treatment coatings and/or ink images or portions thereof or other residual material) is cleaned from the surface of ITM 210;
(e) A processing station 260 upstream from the printing and washing stations and a layer of a liquid treatment formulation (e.g., an aqueous treatment liquid) is applied to the ITM surface, the treatment liquid comprising, by way of example, a dilute solution of a charged polymer; can further include

Those skilled in the art will appreciate that not all of the components shown in FIG. 1 are required. For example, the cooling station and cleaning station can be combined into a single station that can also serve the cooling function of cooling the ITMs before continuing to the imaging station 212 .

An example of a processing station 260 is shown schematically in FIG.

In the particular non-limiting embodiment of FIG. 2, the ITM 210 is generally designated 2014 and is shown as represented by arrow 2012 on a doctor blade suitably mounted within tank 2016. from right to left (ie, as part of a lower run of clockwise rotation). In FIG. 2, doctor blade 2014 is formed from a rigid bar with a smooth, regular cylindrical surface that extends across the width of ITM 210 .

Prior to passing over doctor blade 2014 , the underside (ie, bottom run) of ITM 210 is coated with excess treatment formulation (eg, solution) 2030 . The manner in which the excess treatment formulation (eg, solution) is applied to the ITM 210 is of fundamental immaterial importance to the present invention, and the ITM 210 is simply submerged, for example, in a tank containing the liquid, shown in FIG. A treatment formulation (eg, solution) 2030 may be passed over a fountain 1128 as shown or sprayed by an upward jet (not shown).

As shown in this figure, the ITM 210 has a liquid coating 2030 that is thicker than desired or significantly thicker as it approaches the doctor blade 2014 . The function of doctor blade 2014 is to remove excess liquid 2031 from ITM 210 and ensure that the remaining liquid is spread evenly and evenly over the ITM 210 surface. In a non-limiting example, doctor blade 2014 can be driven toward ITM 210 while ITM 210 is maintained under tension.

Those skilled in the art will appreciate that the treatment liquid can be applied to the ITM by other means and excess liquid 2031 can be removed by other means.

Various materials can be used in the operation of digital indirect printing systems such as those described herein. Examples of materials include inks and ink components, substrates (paper, plastic, metal, or any other material to be printed on), cleaning fluid(s), cooling solution(s), and Contains treatment formulation(s).

In another example, ITM 210 can include a surface release layer that includes silicon and silicon-based materials. Any of the above materials, alone or in combination, can dry, chip, flake, crumble, or otherwise create unwanted particles of foreign matter within the physical confines of the printing system. have a nature. Such foreign particles may, for example, adhere to the sticky surface of the treatment formulation 2030 and form a thin layer on the surface of the ITM 210 . The ITM 210 circulates or rotates at high speed through the various stations that make up the printing system, picking up such particles via physical, chemical or electrostatic Particles may be transported in the print direction at velocities greater than 2.5 m/s, or greater than 3 m/s.

Referring now to FIG. 3, some embodiments of the printing system are shown in greater detail. Printhead 223 is shown positioned above ITM 210 at a height or gap G1 from the surface. For convenience and clarity, printheads 223 are illustrated as continuous in FIG. 3 and subsequent figures, but they need not be continuous, and in some embodiments adjacent printheads Spaces may be provided between and other devices, such as heaters, may be juxtaposed between adjacent printheads. Although G1 is set as the minimum gap to take into account irregularities in the layer of treatment formulation 2030 on the surface of the ITM 210, the average or normal gap takes into account such irregularities. , or may be defined based on considerations of specifications of the printing system and its various components, including but not exhaustive of concentration, jet distance, or droplet size. Such irregularities can be on the order of microns or tens of microns, depending on a number of factors, such as the design of processing station 260, for example. Gap G1 can be on the order of hundreds of microns, 1000 microns, or greater than 1000 microns. In the example shown in this figure, foreign particle 301 is transported by ITM 210 as it rotates in the direction indicated by arrow 2012 (also referred to as the print direction). Particle 301 can be larger than gap G1 in at least one dimension or height above the surface of ITM 210 . The term "height above the surface of the ITM 210" is substantially above the surface of the ITM 210, even if the ITM is "perpendicular" with respect to the ground, such as the cross-section of the ITM opposite particle 301 in FIG. means vertical dimension. If particles 301 continue to be transported by ITM 210 until they reach image forming station 212 or vice versa, particles 301 will in the future or potentially fall into one or more of print bars 222A-222D, specifically collides with the print head 223 therein. If particles 301 have sufficient mass or sufficient momentum, particles 301 may damage print head 223 or its components as a result of such collisions. Alternatively, even if no damage to the elements of the printhead 223 occurs, particles may become lodged or lodged therein or thereon.

It may be desirable to detect such a potential collision prior to its occurrence, and for that purpose a detection system 310 is provided upstream of the imaging station 212 according to the present invention. Detection system 310 is preferably configured to detect all foreign particles 301 prior to all potential future collisions with elements of imaging station 212 . The detection system 310 is more preferably configured to detect all such foreign particles 301 having at least a predetermined intensity of impact and a predetermined probability of impact with an element of the imaging station 212, Further, foreign object particles 301 are configured to be detected in time to take anti-collision or collision avoidance actions.

It can be seen in FIG. 3 that detection system 310 is positioned at position L1 upstream of upstream roller 242 (meaning at least the elements of detection system 310 face position L1 on ITM 210). In another embodiment, the detection system is positioned at position L2 where ITM 210 meets upstream roller 242, ITM 210 is vertical, and the normal vector to ITM 210 is horizontal. The ITM 210 tends to be in tension, and this tension can smooth out irregularities in the surface of the ITM 210 itself or in a thin coating of the treatment 2030 formulation thereon, which irregularities may It may be desirable to detect foreign objects at the location where the ITM 210 contacts the rollers, as this can otherwise complicate effective detection of foreign objects. In some alternative embodiments, the detection system is positioned 90° clockwise around the upstream roller 242 in the print direction L3, i.e., the upstream roller 242. In another alternative embodiment, the detection system is located downstream of upstream roller 242 and upstream of imaging station 212 at location L4.

A location on ITM 210 that faces detection system 310 is referred to herein as a "detection location." In embodiments where detection system 310 includes a detection element (not shown in FIG. 3), the term "detection location" specifically refers to a location on the ITM that faces the detection element.

FIG. 4A includes a perspective view from "top" to "right" looking downstream and looking "below" the image bearing surface of ITM 210, the terms "top" and "bottom" referring to the position where ITM 210 is the detection system. Relatively used for the non-limiting example of being locally horizontal within the area of 310e. As this figure shows, the perspective view may be defined by an X-axis, a Y-axis, and a Z-axis, which are parallel to the floor (not shown), orthogonal to each other, and together. defines a plane at , and the y-axis is orthogonal to that plane. Thus, "horizontal" as used herein has the meaning of being placed in or on the xz plane that is parallel to the floor, and "vertical" as used herein. has the meaning of being arranged in the Y direction, in particular orthogonally to the XZ plane. As discussed above, ITM 210 may be locally horizontal or locally vertical within the area of the detection system (eg, detection system 310e). Note that all other perspectives 4B, 5, 6A, 6C, 7, 8A, and 17B utilize this same perspective to illustrate their respective embodiments. want to be

In the embodiment shown in FIG. 4A, detection system 310 is elongated, oriented in the cross-print direction, and has proximate edges 421 adjacent ITM 210 with gap G2 therebetween as shown in FIG. 4C. and a machine detection system 310e including blade 410 displaced as a result. Although the respective edges of blades 410 are illustrated in the various drawings as being flat or curved, their shape is not critical and the edges of blades 410 can have any shape. The detection position is chosen to be the position where the ITM 210 is vertical, e.g. the machine detection system 310e is positioned facing either position L1 or position L2 (shown in FIG. 3). Alternatively, the detected position is such that the ITM 210 is horizontal, as shown in FIG. 4C, during normal operation of the printing system without any foreign object impact. and, for example, if machine detection system 310e is positioned facing either position L3 or location L4 (shown in FIG. 3), as shown in FIG. 4C, The blade 410 is vertical during normal operation of the printing system without any foreign object impact. As shown in FIG. 4A, the width of blades 410 extends along most of the width of ITM 210, and as shown in FIG. There may be a plurality of adjacent blades 410 provided side by side across the width of the ITM 210 with a gap G4 therebetween. In some embodiments, the total width of all blades 410 excluding gap G4 is at least 99% of the width of ITM 210 . In some embodiments, the total width of all blades 410 excluding gap G4 is at least 99.5% of the width of ITM 210 . In some embodiments, the total width of all blades 410 excluding gap G4 is at least 99.7% of the width of ITM 210 .

Blade 410 is preferably a "floating blade". This is because if the blade 410 is struck by a foreign particle 301 carried by the ITM 210 on or near the proximal edge 421 (e.g., point P1 in FIG. 5A) on the face of the blade 401, It means that the rotational motion of the proximal edge 421 is relatively unconstrained.

FIG. 5A is a non-limiting illustration of a floating blade 410 having a proximal edge 421 adjacent to or facing the surface of ITM 210 and displaced therefrom by a gap G2 therebetween, as shown in FIG. 7C. for example. 5A, 5B, 5C, and 5D all show ITM 210 as locally vertical and blade 410 as horizontal for convenience only, and in some embodiments: It is understood that the opposite is true, and thus the relative orientations of major elements shown in these figures are only illustrative of the structure and function of the various system elements shown. sea bream. As shown, blade 410 is disposed on a pivot mechanism 411 fixedly mounted to rigid frame element 415 a and is pivotable with degrees of freedom indicated by arrow 414 . Considering that FIG. 5A is an elevation view, those skilled in the art will recognize that arrow 414 is perpendicular to the vector of print direction 2012 and about an axis that is parallel to the width dimension of ITM 210, as will now be explained. be understood to indicate a pivot rotation or rotation of the . FIG. 5A shows the XY axis so that the print direction 2012 can be understood to be upward in the Y direction (this XY axis is viewed in the perspective of FIG. 5A as FIG. 5a is a two-dimensional projection). (shown as including the Z-axis, which cannot be moved). It can be seen that the cross section of blade 410 extends lengthwise in the X direction from distal edge 422 to proximal edge 421, and the thickness of blade 410 is shown in the Y direction. Therefore, the width of blade 410 is necessarily in the Z direction (not shown). Similarly, the width of ITM 210 is in the Z direction, and the axis of rotation of blade 410 about pivot mechanism 411 is similarly arranged in the Z direction. The pivot axis thus extends across the width of blade 410 . In other embodiments (not shown), the pivot mechanism 411 is an integral part of the rigid frame element 415a, e.g. such as elongated spikes or elongated triangles of rigid frame element 415a material.

Pivot mechanism 411 can have a sharp triangular top edge, shown for convenience in the drawings, or, for example, as long as blade 410 is free to pivot on it as described with respect to degree of freedom arrow 414 above. It can have rounded edges. A distal edge 422 of blade 410 is linked to rigid frame element 415b by linking means 416, which in this example comprises a tension spring. Linking means 416 keeps blade 410 horizontal in its rest configuration, including position, length and tension (meaning during normal operation of the printing system when there is no impact between foreign objects and blade 410); It serves to define the precise vertical position of its proximal edge. In some alternative embodiments, linking means 416 may include a pneumatic piston and cylinder (not shown). Linking means 416 acts to limit, reduce, or dampen downward movement of distal edge 422 of blade 410 when an upward force is applied to proximal 421 edge of blade 410 . Although the above discussion was used to describe an example where the blade 410 is horizontal when the linking means 416 is in the rest position, those skilled in the art will appreciate that in other embodiments the linking means 416 is not horizontal, i.e. , can serve to maintain the position of blade 410 with distal edge 422 higher than proximal edge 421 or vice versa. Such determination of the exact angle of rest of blade 410 in the rest configuration is not exhaustive, and when considering parameters such as allocated space, dimensions of blade 410, and mechanical properties of linkage means 416, Done by the system designer. Similarly, it will be appreciated that if the machine detection system 310e is positioned vertically in a position where the ITM 210 is locally horizontal, the blade 410 may be at a vertical or near-vertical rest angle. want to be

The blade 410 is configured so that it cannot lift and lose contact with the pivot mechanism 411 when an upward force (which should reduce the downward movement of the distal edge if it occurs) is applied to the proximal edge. preferably. For example, the weight of the blade 410 can be adjusted for this, or additional weight can be added to the blade either globally or alternatively locally along the area of the pivot mechanism 411. be able to. Alternatively, blade 410 may be connected to pivot mechanism 411 in a manner that allows blade 410 freedom to pivot in the direction indicated by arrow 414, but does not restrict rotational movement within the desired range. This connection (not shown) is not exhaustive and can include any known mechanical connector including nails, rivets, bolts, screws, steel wire snares, restraining brackets, or bearings. Alternatively, blade 410 may be "pinned" onto pivot mechanism 411 by a mechanical member (not shown) fixedly attached to a rigid frame element, such as rigid frame element 415b.

The detection system 310e shown in FIGS. 5A, 5B, 5C, and 5D measures the extension H ₃₀₁ of the particles 301, 302 from the surface of the ITM 210 (i.e., " _5A ) is greater than the value of the gap G2 between the proximal edge of blade 410 and the surface of ITM 210, indicated by arrow 2012. Foreign particles 301 , 302 carried by the ITM 210 in a direction that is directed toward the blade 410 are configured to impact the proximal edge of the blade 410 . As shown in FIG. 5B, foreign particles 302 are smaller than gap G2 and pass through blade 410 without impacting blade 410, whereas larger particles 301 are larger than G2 and impact blade 410. give. Therefore, the value of gap G2, i.e., the proximity of blade 410 to the surface of ITM 210, is less than the value of G2, and foreign particles protruding from the surface of ITM 210 do not or are less likely to collide with print head 222. Or it turns out to be a design choice based at least in part on the assumption that the probability of collision is extremely low and can be "ignored."

5C, which shows detection system 310e later than FIG. 5A or 5B, foreign particle 301 impacts proximal edge 421 of blade 410, causing blade 410 to pivot on pivot mechanism 411, "counterclockwise (for this non-limiting illustrated example) exerted a rotational force on blade 410 causing downward movement of distal edge 422 of blade 410 . The linking means 416 limits or dampens the downward movement of the distal edge 422 so that the downward movement of the distal edge 422 caused by the foreign particles 301 impacting the distal edge 422 of the blade 410 is reduced by impact force. Its range is limited according to its strength.

According to embodiments, the machine detection system identifies the orientation of the blade and/or detects deflection of the blade after, for example, a foreign object carried by the ITM impacts and causes the blade to pivot. , including the blade orientation detector. A blade orientation detector can include any combination of mechanical, magnetic, optical, electronic, and software elements. An example of a mechanical component of a blade orientation detector is a limit switch. As shown in the non-limiting examples of FIGS. 5A, 5B, 5C, and 5D, machine detection system 310e also emits current when physically contacted by distal edge 422 of blade 410. A limit switch 412 may be included that is configured to turn on or facilitate. In a properly designed machine detection system 301e, the limit switch 412 and other components of the system will use limit switch 412 to ensure that action is taken to prevent potential future collisions of particles 301 with the printhead. Switch 412 is configured to become contacted by distal edge 422 as a result of an impact (between foreign particle 301 and proximal edge 421) of sufficient strength. Current switched on or driven by limit switch 412 can be used to automatically perform actions, as described below. An example of a suitable limit switch 412 is a miniature snap-action switch such as the "Micro Switch™" product known in the electronics and mechanical industries. The term micro-switch is used interchangeably herein with other known terms such as limit switch or snap-action switch and is actuated by physical force, for example through the use of a tipping point mechanism. means any electrical switch that

The minimum impact intensity “INT _MIN ” is used herein to mean the minimum impact intensity between a foreign object and the printhead that has the potential to cause damage to the printhead. The minimum impact strength INT _MIN represents or can be calculated by either momentum or force, the value of which is calculated by the system designer, or alternatively, empirically through trial and error or after the fact. can be determined. For example, the designer has determined that the impact intensity resulting from impact with a printhead by a foreign particle having a mass of 5 milligrams moving at a speed of 2 meters per second (i.e., transported by the ITM) will damage the printhead. It can be calculated or determined to result in the minimum possible crash strength. This particle has a momentum of 10 mg-m/sec. If this particle strikes a stationary printhead and decelerates to zero velocity in 1 millisecond, the stopping force acting on the particle should be 10 g-m/sec/sec (simplified For the sake of the example, this ignores the effects of both particle and printhead deformations and assumes that the printhead does not move). Therefore, the minimum impact intensity INT _MIN for this example can be expressed as either a particle momentum of 10 mg-m/sec or an impact force of 10 g-m/sec/sec. The strength of the impact between the foreign object and a detector or sensing element such as the proximal edge 421 of the blade 410 can be used to predict the strength of potential future collisions between the foreign object and the printhead; Therefore, INT _MIN is the minimum magnitude of impact strength between foreign particle 301 and proximal edge 421 of blade 410 that must trigger action to avoid or prevent future collisions. can be used.

For example, the minimum impact strength derived from INT _MIN to cause or allow blade 410 to contact limit switch 412 and trigger anti-collision action is the actual theoretical or It will be apparent to those skilled in the art that a safety factor can be taken to set the impact strength below the empirical minimum impact strength. Therefore, the minimum impact strength discussed in connection with FIGS. 5C and 5D is determined by the amount of momentum or impact force actually required for a foreign particle to cause damage to the printhead (i.e., , INT _MIN ), or 2/3, 1/2, 1/3, or any other fraction. Those skilled in the art will understand that an impact will occur only if the amount of extension of a foreign object such as H ₃₀₁ in FIG. be understood by

Linking means 416 is arranged such that an impact having a strength equal to or greater than the minimum impact strength constant INT _MIN causes the trailing edge to move downward to the extent that it contacts and activates limit switch 412 at contact point C1. , and an impact having an intensity less than INT _MIN does not cause the trailing edge to travel downward to the extent that it contacts and activates limit switch 412 (or, in some embodiments, the trailing edge (prevents the edge from moving downward). This can be achieved, for example, by choosing a tension spring with suitable properties of length and tension. As can be seen, the impact strength in FIG. 5C is less than INT _MIN and the distal edge of blade 410 does not contact limit switch 412 at contact point C1, whereas in FIG. 5D the impact strength is less than INT _MIN . Beyond, the distal edge of blade 410 actually contacts limit switch 412 at contact point C1.

FIG. 6A illustrates that detection system 310 includes miniature laser transmitter 151 and miniature laser receiver 151 to ensure or trigger an anti-collision response that should be effective before particle 301 reaches imaging station 212 . 152, respective pedestals 155a and 155b, and foreign particles 301 that process signals from laser transmitter 151 and laser receiver 152 and interrupt or traverse laser beam 154 as carried by rotating ITM 210. , a laser-based detection system 310a including pre-programmed electronic circuitry 160 that calculates whether particles 301 have sufficient size and mass when considered together with their transport velocity. . In this embodiment, laser beam 154 is parallel to the surface of ITM 210, traverses the width of ITM 210, and is displaced from ITM 210 by a height or gap G2 shown in FIG. 6B. Examples of suitable laser beam detection systems for this embodiment are the LV-S71 and LV-S72 Small Beam Spot Thrubeam laser sensors commercially available from Keyence Corporation of America, Itasca, Illinois, USA. In any of the embodiments herein, the gap G2 is the gap between the printhead 223 and the ITM to predict future or potential collisions with the printhead 223 of foreign particles 301 of size greater than or equal to G1 or somewhat smaller than G1. 210 is preferably smaller than the gap G1 characterizing the gap between . For example, the value of gap G2 can be set to be no more than 50%, no more than 70%, or no more than 90% of the value of G1, or alternatively at least 50% of the value of G1. %, at least 70%, or at least 90%.

In an alternative embodiment shown in FIG. 6C, laser detection system 310b uses a miniature laser transmitter to ensure or trigger an anti-collision response that should be effective before particle 301 reaches imaging station 212. 151 , base 155 a , laser reflector 153 , laser transmitter 151 , and foreign particles 301 that process signals from laser transmitter 151 and interrupt or traverse laser beam 154 as carried by rotating ITM 210 . pre-programmed electronic circuitry 160 that calculates whether it has sufficient size and mass when considered together with the transport speed of . An example of a suitable laser detection system for this embodiment is the LV-S61 Small Beam Spot Retro-Reflective laser sensor commercially available from Keyence Corporation of America, Itasca, Illinois, USA.

In one example, the blade orientation detector can include a camera and image processing software. FIG. 7 illustrates that detection system 310 includes one or more viewing range cameras 163 and at least one 163 to ensure or trigger an anti-collision response that should be effective before particle 301 reaches imaging station 212 . Images from one lateral base 157 , an opposing base 157 a , and one or more cameras 163 are processed so that foreign particles 301 imaged by the one or more cameras 163 are projected onto the ITM 210 . shows an embodiment that includes a visual camera system 310c that includes pre-programmed electronic circuitry 161 that calculates whether it has sufficient size and mass when considered together with the transport speed of . As can be seen from this figure, one or more cameras 163 can be deployed alongside the ITM 210 to image the moving surface of the ITM 210; can be deployed opposite or facing the moving ITM 210 at a distance that takes into account the angle of capture of the camera 163 and the width of the ITM 210, which will be appreciated by those skilled in the art of imaging systems. can divide the coverage of the ITM 210 widthwise among multiple cameras 163 to allow the cameras to be placed closer to the ITM 210 . An example of a suitable camera for this embodiment is the In-Sight® Micro 8000 series smart camera available from Cognex Corporation of Natick, Massachusetts, USA. The vision cameras referred to herein can record still images and/or motion pictures.

In another embodiment shown in FIGS. 8A and 8B, the detection system 310 is an acoustic-based system including strings 164 including flexible members held under tension by, for example, adjustable string attachment elements 158a and 158b. Includes detection system 310d. String 164 may comprise a single material such as nylon or steel, or multiple materials in which a first material, such as a copper alloy, is wrapped around a core material such as steel or nylon. Strings 164 may alternatively or additionally include other materials, with material selection being the desired pitch or pitch when struck by foreign particles 301 carried by rotating ITM 210 . Vibration over a range and desired amplitude or range of amplitudes. As shown in FIG. 8B, the chord spans the ITM 210 widthwise, with a gap G2 therebetween, such that the attachment elements 158a and 158b are located on opposite sides of the ITM 210. is preferably displaced from . Acoustic-based detection system 310c processes tones produced by microphone 165 and string 164 to ensure or trigger an anti-collision response that should be effective before particle 301 reaches imaging station 212. , a pre-programmed It preferably further includes electronic circuitry 162 .

Referring now to FIG. 9, in some embodiments a method of operating a printing system comprises:
a) step S01 forming an ink image on the surface of the ITM 210 by droplet deposition;
b) step S02 transporting the ink image towards the printing station;
c) step S03 transferring the ink image to the substrate;
d) step S04 detecting the presence of a foreign object carried by the rotating ITM;
e) preventing potential collisions between the foreign object and the printhead by taking action in response to the detection in step S05 S04.

In some embodiments, not all of the method steps are required.

In some embodiments, step S04 is performed by a detection system including at least one of a laser detector system, an image processing system including a visual camera, an acoustic detection system, and a mechanical detection system. Examples of suitable laser detector systems are discussed above with respect to Figures 6A, 6B, and 6C. Examples of suitable image processing systems including vision cameras were discussed above with respect to FIG. Examples of suitable acoustic detector systems are discussed above with reference to FIGS. 8A and 8B. Examples of suitable machine detection systems are discussed above with respect to FIGS. 4A, 4B, 4C, 5A, 5B, 5C, and 5D.

In some embodiments, step S05 is the amount of time that elapses between detection of a foreign object and arrival of the foreign object at the position of the printhead or at a point on the ITM 210 facing the printhead is acceptable. Including performing collision avoidance actions within response time. This acceptable response time for prevention of potential collisions depends on the rotational speed of the ITM and the distance between the detection position (where the presence of a foreign object is detected) and the printhead (or an upstream position on the ITM surface facing the printhead). is defined by the distance along the ITM surface of The response time can be less than 1 second, less than 500 milliseconds, or less than 200 milliseconds.

In FIG. 10, a method of operating a printing system, such as that discussed above with reference to FIG. 9, determines that the expected strength of potential collisions with the printhead exceeds a predetermined threshold of minimum collision strength INT _MIN . can include calculating, determining or designing in whether Q1 exceeds or not, depending on the result, the method will not respond to step S09, i.e., take no action to prevent a potential collision. Alternatively, it will be appreciated that step S05 may instead include performing a collision avoidance action. The calculations or determinations are performed by a detector system including electronic circuitry including programmed instructions such as those discussed above with reference to FIGS. 6A, 6B, 6C, 7, 8A, and 8B. can do. The designed-in pass/fail of whether the expected strength of a potential collision exceeds a predetermined threshold is shown above in FIGS. 4A, 4B, 4C, 5A, 5B, 5C, and 5D. can be resolved with reference to the discussion of the detection system including the blade 410 discussed with reference to.

In some embodiments, preventing potential collisions step S05 includes raising the printhead before a foreign object can strike the printhead.

In some embodiments, preventing potential collisions step S05 includes moving the surrogate to a position upstream of the printhead so that the foreign object collides with the surrogate rather than the printhead.

FIG. 11 illustrates a method of operating a print head comprising:
a) step S11 forming an ink image on the surface of the ITM 210 by droplet deposition;
b) step S12 of transporting the ink image towards the printing station;
c) a step S13 of transferring the ink image to the substrate;
d) step S14 of detecting an impact between the sensing element and a foreign object carried by the rotating ITM;
e) responding to the impact detection by performing at least one anti-collision action S15.

In some embodiments, not all of the method steps are required.

Examples of apparatus suitable for performing step S14 of detecting an impact between the sensing element and a foreign object carried by the rotating ITM 210 are described above in FIGS. 5C and any of the embodiments discussed in connection with FIG. 5D.

In some embodiments, step S15 is performed between the detection of the foreign object and the arrival of the foreign object at the position of the printhead or at a point on the ITM facing the printhead before the printhead is lifted away from the ITM. Including performing collision avoidance actions within the amount of time that elapses. This acceptable response time for prevention of potential collisions depends on the rotational speed of the ITM as well as the speed along the ITM surface between the location where the presence of the foreign object is detected and the printhead or upstream location on the ITM surface facing the printhead. defined by the distance The response time can be less than 1 second, less than 500 milliseconds, or less than 200 milliseconds.

In FIG. 12, a method of operating a printhead, such as that discussed above with reference to _FIG . may include a designed-in pass/fail Q2 of whether or not to exceed, depending on the result, the method may choose not to take action to prevent step S19 no response or potential collision, or alternatively It will be appreciated that the execution of anti-collision actions in step S15 may be included. The designed-in pass/fail of whether the expected strength of a potential collision exceeds a predetermined threshold is shown above in FIGS. 4A, 4B, 4C, 5A, 5B, 5C, and 5D. can be resolved with reference to the discussion of the detection system including the blade 410 discussed with reference to.

In some embodiments, preventing potential collisions step S15 includes raising the printhead before a foreign object can strike the printhead.

In some embodiments, preventing potential collisions step S15 includes moving the surrogate to a position upstream of the printhead so that the foreign object collides with the surrogate rather than the printhead.

13A and 13B, a printing system including a detection system 310e, such as any of the systems shown in FIGS. 4A, 4B, 4C, 5A, 5B, 5C, and 5D. Several component embodiments of 100 are shown. Detection system 310e is positioned such that proximal edge 421 of blade 410 is at opposite position L2. FIG. 13A shows the situation of the system at time= _T1 when the foreign particle 301 is still upstream of the detection position L2 and the blade 410 is still horizontal. FIG. 13B shows particle 301 impacting the proximal edge of blade 410 causing blade 410 to pivot, and particle 301 continuing to be transported by ITM 210 after impact potentially colliding with print head 223. Shown is the situation of the system at time= _T2 after reaching the position that should occur. Since the strength of the impact was greater than INT _MIN , similar to the example shown in FIG. It was enough to contact 412.

Contact with the micro switch 412 is an example of a display in which Q2 of the impact detection in step S14 of _FIG . is. The anti-collision action according to step S15 of _FIG . there is The anti-collision action taken included raising print bar 222 with print head 223 before foreign objects could collide with the print head. The gap between print head 223 and ITM 210 is no longer equal to G1 as in FIG. 13A, but G3, which is greater than G1. In one example, G1 is 1 mm and G3 is 15 mm. In another example, G1 is 2 mm and G3 is between 4 and 10 mm. In yet another example, G1 is 800 microns and G3 is 8 mm. In the embodiment shown in this figure, a printbar frame 225 was used to lift all of the printbars 222 simultaneously as part of the anti-collision action. In an alternative embodiment (not shown), one or more individual printbars 222 may be configured in the same manner as described above if the design of the particular printing system is sufficient to prevent collisions. can be lifted by

In the embodiment shown in FIG. 14A, the pre-programmed electronics 160 provided in various embodiments for the detection discussed herein actuate the printbar by raising the printbar frame 225 . 222 is in electrical communication with an electrical actuator 229 configured to lift 222; Thus, a calculation or determination is made by the pre-programmed electronic network 160, e.g., the design-in pass/fail Q1 discussed with reference to _FIG . When resolved affirmatively and it is desired to prevent a potential collision between the foreign object and the printhead as in step S05 of FIG. can be used to lift the print head 223 to a predetermined distance of . In this discussion of FIG. 14A, depending on the respective embodiment of detection system 310a, 310b, 310c, or 310d selected, pre-programmed electronic circuitry 160 is replaced with pre-programmed electronic circuitry 161 or pre-programmed electronic circuitry 161 or It is clear that the electronic circuitry 162 can be replaced with a programmed .

In the embodiment shown in FIG. 14B, the limit switch 412 provided in the various embodiments for shock detection discussed herein causes the print bar 222 to be lifted by raising the print bar frame 225. is in electrical communication with an electrical actuator 229 configured as Thus, for example, the design-in pass/fail Q2 "does the severity of the crash exceed threshold INT _MIN ?" discussed with reference to FIG. 410 and is desired to respond to impact detection by performing at least one anti-collision action as in step S15 of FIG. It can be used to lift the print head 223 away from the surface of 210, eg, to a predetermined distance of G3.

An example of an electrical actuator suitable for any of the above embodiments is the Model PA-15 High-Speed Linear Actuator available from Progressive Automations of Richmond, British Columbia, Canada. However, any fast actuator capable of performing anti-collision actions within the response time is suitable. Those skilled in the art will appreciate that multiple electric actuators may be required to effectively lift the printbar within an acceptable response time, and that pneumatic actuators can replace electric actuators. Further, the use of a piston actuator is a disclosed design choice as an example and is only one of several possible ways to effectively lift the printbar, and any form of mechanical device can be designed. It should be clear to the system designer that the same result of quickly lifting the printbar within an acceptable response time can be achieved.

FIG. 15 illustrates a method of operating a printing system comprising: a) step S21 detecting an impact between a blade element of the detection system and a foreign object carried by a rotating ITM;
b) Step S22 Subject to an affirmative resolution of the designed-in pass/fail Q6 of whether the expected intensity of a potential impact with the print head exceeds a predetermined threshold INT _MIN for minimum impact intensity, the foreign object is Responding to the shock detection by lifting the printbar away from the ITM in less time than it takes to reach the printbar, whereby in the case of a negative resolution of pass/fail Q6 the method steps Responding to impact detection, including non-response of S29;
c) Step S23: YES resolution to decision Q7 whether the expected severity of a potential collision with the print head exceeds a predetermined threshold INT _MAX of maximum collision severity requiring further responsive collision prevention action. provided that the method further responds to the impact detection by stopping rotation of the ITM, whereby the method includes no further response in step S30 in the case of a negative resolution of decision Q7. Fig. 10 shows an embodiment further comprising responding;

In some embodiments, not all of the method steps are required.

In some embodiments, step S23 of further responding to the impact detection by stopping rotation of the ITM may be based at least in part on an operator decision regarding resolution of decision Q7.

The method of FIG. 15 is an embodiment in which the rotational motion of blade 410 of machine detection system 310f is imaged by line-of-sight camera 191 and the images captured by camera 191 are processed by pre-programmed electronic circuitry 167. can be better understood in view of the following discussion of Figures 16A, 16B, 16C, and 16D, which show a set of Accordingly, camera 191 and electronics 167 of FIGS. 16A, 16B, 16C, and 16D replace limit switch 412 of FIGS. 5A, 5B, 5C, and 5D, while the other illustrated All of the components are structurally and operationally identical.

In Figure 16A, the machine detection system 310f is "waiting" for an impact and the foreign particle 301 moves in the printing direction, i.e., the imaging station and its printbar and printhead (all not shown in Figure 16A). It can be seen as being transported towards the ITM 210 .

FIG. 16B shows machine detection system 310f at a later time than FIG. It can be seen that a "counterclockwise" rotational force was applied, causing downward movement of the distal edge of blade 410 to an angle of θ ₁ below horizontal. Linking means 416 links trailing edge 422 to the extent that an impact having an intensity equal to or greater than the minimum impact intensity constant INT _MIN causes detection of trailing edge 422 by camera 191 and preprogrammed electronic circuitry 167 to trigger a responsive anti-collision action. is preferably configured to allow the downward movement of the .

In Figure 16B, the impact strength is less than INT _MIN . INT _MIN is described above and has the same meaning and purpose here. In the example of FIG. 16B, camera 191 captures an image of blade 410 pivoted by an angle of θ ₁ from horizontal, and electronics 167 determines that the pivot rotation of angle θ ₁ has an intensity less than INT _MIN . It is pre-programmed with design information that represents a shock, that is, Q6 of FIG. 15 resolves to negative and that the "no response" step S29 is performed instead of the "response" step S22.

FIG. 16C shows a scenario where the impact of particle 301 with blade 410 has greater intensity than the impact of FIG. 16B. This is evidenced by the larger (from FIG. 16B) rotation angle θ ₂ (ie, θ ₂ >θ ₁ ), and indeed when this angle is captured by camera 191, electronic circuitry 167, for example, detects the angle and impact Using a pre-programmed lookup table of intensities, we determine that the impact in this scenario has an intensity greater than INT _MIN , so Q6 in FIG. 15 is resolved affirmatively. This lookup table indicates that angle θ ₂ indicates an impact strength less than INT _MAX , thus Q7 of FIG. can be further used to determine that INT _MAX is another value calculated based on the momentum of the particles at the time of impact or the force of impact, and indicates impacts that are likely to cause more severe levels of damage to imaging station components.

FIG. 16D shows a scenario in which the collision of particle 301 with blade 410 has greater intensity than either impact of FIGS. 16B and 16C. This is evidenced by a larger rotation angle θ ₃ (ie θ ₃ ≧θ ₂ ), and indeed when this angle is captured by the camera 191 the electronic circuitry 167 is pre-programmed for e.g. By using the modified lookup table, the impact of this scenario is greater than INT _MIN (thus resolving Q6 in FIG. 15 positively) and greater than INT _MAX (thus resolving Q7 in FIG. 15 positively). solve) strength.

The preprogrammed electronics 167 of the embodiment shown in FIGS. 16A, 16B, 16C, and 16D were configured to lift the printbar 222 by, for example, raising the printbar frame 225. Providing an electrical impulse to the electrical actuator 229 of FIG. 14A may be configured to trigger a responsive anti-collision action. In any discussion of FIG. 14A, it should be apparent that pre-programmed electronics 160 may be replaced by pre-programmed electronics 167 depending on the respective embodiment of detection system 301 selected. be. The pre-programmed electronic circuitry 167 of the embodiments shown in FIGS. 16A, 16B, 16C, and 16D can, for example, automatically stop rotation of the ITM 210 or stop rotation of the ITM 210. It may further be configured to trigger further responsive anti-collision actions by displaying or sounding an alarm that indicates to the operator that it should.

17A and 17B illustrate that anti-collision or anti-collision action according to any of the embodiments disclosed herein moves surrogate 307 in front of (upstream) print head 223 within response time, which shows an alternative embodiment that includes preventing foreign particles 301 from colliding with print head 223 . Instead, the foreign object collides with the surrogate. As shown in these figures, the surrogate 307 is preferably sufficient not to impede movement of the ITM 210 and not scrape the dried treatment formulation 2030 (shown in FIG. 2) from the ITM 210. Elongate members placed along the surface of the ITM 210 in the width direction away from the surface of the ITM 210 and sufficiently close (preferably with a gap of less than G2) to ensure eventual removal of impacts and foreign objects. is. It can be seen in both FIGS. 17A and 17B that the time is T ₂ and the surrogate 307 has deployed in response to the impact of the foreign particle 301 with the blade 410 .

FIG. 18A shows a surrogate 307 in the form of an elongated member positioned widthwise along the surface of the ITM 210 stored in a position above the surface of the ITM 210 (i.e., an impact force requiring responsive anti-collision action). 30 shows an alternative embodiment in which the retracted position is reached by pivoting through the use of hinge 309 (while “waiting” for detection).

FIG. 18B, which is a plan view of a section of the ITM 210 upstream of the imaging station 212 shown in FIG. Into position, by an electrical actuator (not shown) or other suitable mechanical means, surrogate 307 is quickly slid from a storage position away from the side of ITM 210 into a home position spanning the width of ITM 210 and surrogate 307 is shown by arrow 901. Fig. 10 shows another alternative embodiment with forward and backward movement capability in the indicated directions; In some embodiments, the surrogate 307 includes protrusions 311 configured to remove from the surface of the ITM 210 any particles 301 of foreign matter that have collided with the surrogate, the removal being a latent particle with the print head 223 . This occurs when the surrogate 307 is retracted from being positioned widthwise across the surface of the ITM 210 after the target collision has been deflected (by the foreign object striking the surrogate instead).

The present invention has been described using detailed descriptions of embodiments of the invention that are provided by way of example and are not intended to limit the scope of the invention. The described embodiments include different features, and not all of these features are required in all embodiments of the invention. Some embodiments of the present invention utilize only some of the possible features or combinations of features. Variations of the described embodiments of the invention, as well as embodiments of the invention comprising different combinations of the features noted in the described embodiments, will occur to those skilled in the art.

In the description and claims of this disclosure, the verbs "comprise," "include," and "have," and their cognates, are used when one or more objects of the verb are , is used to indicate not necessarily the complete list of one or more subject members, constituents, elements, or parts of the verb. As used herein, the singular forms "a," "an," and "the" include plural forms unless the context clearly dictates otherwise. For example, the terms "a marking" or "at least one marking" may include multiple markings.

Claims (33)

A printing system,
a. An intermediate transfer member (ITM) comprising a flexible endless belt mounted on a plurality of guide rollers, said endless belt defining longitudinal and lateral directions along the circumference of said endless belt. , said lateral direction is (i) perpendicular to said longitudinal direction and (ii) along the width of said endless belt;
b. An imaging station including a print bar disposed over the surface of the ITM, the print bar configured to form an ink image on the surface of the ITM by droplet deposition. and,
c. a conveyor for driving the rotation of the ITM at a fixed rotational speed in the print direction to transport the ink images toward a printing station where they are transferred to a substrate;
d. a detection system configured to detect foreign objects transported by a rotating ITM to a detection location upstream of said imaging station and downstream of said printing station;
e. A response operably coupled to the detection system for responding to detection of the foreign object by performing at least one anti-collision action to prevent potential collision between the foreign object and the printbar. A system, wherein the detection system includes a detection element positioned adjacent the ITM at the detection location, the detection element including an elongated blade defining an elongation direction, the elongation direction of the elongated blade being , a response system directed laterally of said endless belt;
printing system, including 2. The printing system of claim 1, wherein the gap (G2) between the sensing element and the ITM does not exceed 90% of the size of the gap (G1) between the printbar and the ITM. The plurality of guide rollers on which the endless belt is mounted includes an upstream guide roller and a downstream guide roller respectively positioned upstream and downstream of the imaging station, and the ITM is positioned at the detection position. 3. The printing system of any one of claims 1-2, in contact with the upstream guide roller. 4. The method of any one of claims 1-3, wherein the distance from the detection position to the imaging station along the path of travel of the ITM in the print direction is less than 10% of the total length of the ITM. printing system. 5. The printing system of any one of claims 1-4, wherein the detection system is configured to detect an impact between the detection element and the foreign object. 5. A printing system according to any preceding claim, wherein the detection system is configured to mechanically detect an impact between the detection element and the foreign object. (i) the print bar includes an inkjet printhead; and (ii) the detection system and the response system determine whether performing the at least one anti-collision action is a future collision avoidance action between the foreign object and the inkjet printhead. 7. A printing system according to any one of the preceding claims, arranged to condition a calculated prediction of the intensity of a crash exceeding a predetermined threshold. a. The response time to prevent potential collisions between the foreign object and the print bar depends on the speed of the rotating ITM and the imaging from the detected position along the path of travel of the ITM in the print direction. defined by the distance to the station and
b. The detection system and the response system are configured such that the at least one anti-collision action is performed within the response time, the response time being less than 1 second.
The printing system according to any one of claims 1-7. 9. The printing system of any preceding claim, wherein the at least one anti-collision action includes lifting the printbar. i. the print bars are positioned over the surface of the ITM with a minimum gap of G1 therebetween;
ii. the response system includes a printbar lift system operably coupled to the detection system for responding to detection of a detected and conveyed foreign object, the printbar lift system including an electrical actuator;
iii. performing the at least one anti-collision action includes lifting the print bar to a height that is at least twice the height of the gap (G1);
iv. Lifting of the print bar is performed within a response time defined by the speed of the rotating ITM and the distance from the detection position to the imaging station along the path of travel of the ITM in the print direction. Ru
10. The printing system according to any one of claims 1-9. Carried by the rotating ITM in a printing system that includes (i) an imaging station where the ink image is formed on an intermediate transfer member (ITM) and (ii) a printing station where the ink image is transferred to a substrate A machine detection system for detecting foreign objects, the machine detection system comprising:
a. elongated blades and
b. linking means including a spring, said linking means linking said blade to a rigid frame;
c. at least one of a limit switch and a camera;
machine detection system, including; 12. The machine detection system of claim 11, wherein the machine detection system is located at a detection location facing the ITM downstream of the printing station and upstream of the imaging station. 13. The machine detection system of any one of claims 11-12, wherein the machine detection system is configured to detect an impact between the foreign object and the elongated blade. 12. The machine detection system is further configured to signal a response system to initiate an anti-collision response to prevent a collision between the foreign object and a component of the imaging station. 14. A machine detection system according to any one of claims 1-13. A print bar forms an ink image on a rotating intermediate transfer member (ITM) comprising a flexible endless belt mounted over a plurality of guide rollers, said endless belt extending around the circumference of said endless belt. defining a longitudinal direction and a lateral direction along, the lateral direction being (i) perpendicular to the longitudinal direction and (ii) along the width of the endless belt, wherein the ink images are aligned with the A method of operating a printing system that is subsequently transported by the ITM to a printing station where substrates are transferred, the method comprising:
a. detecting a foreign object carried by said rotating ITM at a detection position upstream of an imaging station and downstream of said printing station, said detection being positioned adjacent said ITM at said detection position; a detection element comprising an elongated blade defining a direction of elongation, the direction of elongation of the elongated blade being oriented laterally of the endless belt;
b. responding to the detection by performing at least one anti-collision action to prevent potential collision between the foreign object and the printbar;
A method, including A printing system,
a. an intermediate transfer member (ITM) comprising a flexible endless belt mounted on a plurality of guide rollers;
b. An imaging station including a print bar disposed over the surface of the ITM, the print bar configured to form an ink image on the surface of the ITM by droplet deposition. and,
c. a conveyor for driving the rotation of the ITM at a fixed rotational speed in the print direction to transport the ink images toward a printing station where they are transferred to a substrate;
d. a detection system configured to detect foreign objects transported by a rotating ITM to a detection location upstream of said imaging station and downstream of said printing station;
e. A response operably coupled to the detection system for responding to detection of the foreign object by performing at least one anti-collision action to prevent potential collision between the foreign object and the printbar. a system;
a printing system comprising
The plurality of guide rollers on which the endless belt is mounted includes an upstream guide roller and a downstream guide roller respectively positioned upstream and downstream of the imaging station, and the ITM is positioned at the detection position. A printing system in contact with the upstream guide roller. A method of operating a printing system in which a print bar forms an ink image on a rotating intermediate transfer member (ITM) and the ink images are subsequently transported by the ITM to a printing station where they are transferred to a substrate. and the method includes:
a. detecting a foreign object carried by the rotating ITM at a detection location upstream of an imaging station and downstream of the printing station;
b. Responding to the detection by performing at least one anti-collision action to prevent potential collisions between the foreign object and the print bar, the ITMs disposed on a plurality of guide rollers. comprising a flexible endless belt mounted thereon, a plurality of guide rollers on which said endless belt is mounted, an upstream guide roller and a downstream guide roller respectively positioned upstream and downstream of said imaging station; wherein the ITM contacts the upstream guide roller at the sensing location;
A method, including A printing system,
a. an intermediate transfer member (ITM) comprising a flexible endless belt mounted on a plurality of guide rollers;
b. An imaging station including a print bar disposed over the surface of the ITM, the print bar configured to form an ink image on the surface of the ITM by droplet deposition. and,
c. a conveyor for driving the rotation of the ITM at a fixed rotational speed in the print direction to transport the ink images toward a printing station where they are transferred to a substrate;
d. a detection system configured to detect foreign objects transported by a rotating ITM to a detection location upstream of said imaging station and downstream of said printing station;
e. A response operably coupled to the detection system for responding to detection of the foreign object by performing at least one anti-collision action to prevent potential collision between the foreign object and the printbar. a system;
A printing system comprising:
A printing system according to claim 1, wherein a distance from said detection position to said imaging station along a path of movement of said ITM in said printing direction is less than 10% of the total length of said ITM. . A print bar of an imaging station forms ink images on a rotating intermediate transfer member (ITM), said ink images being subsequently transported by said ITM in the print direction to a print station where they are transferred to a substrate. 1. A method of operating a printing system comprising:
a. detecting a foreign object carried by the rotating ITM at a detection location upstream of an imaging station and downstream of the printing station;
b. responsive to said detection by performing at least one anti-collision action to prevent a potential collision between said foreign object and said printbar, said detection along a path of travel of said ITM in said print direction; the distance from a location to the imaging station is less than 10% of the total length of the ITM;
A method, including A printing system,
a. an intermediate transfer member (ITM) comprising a flexible endless belt mounted on a plurality of guide rollers;
b. An imaging station including a print bar disposed over the surface of the ITM, the print bar configured to form an ink image on the surface of the ITM by droplet deposition. and,
c. a conveyor for driving the rotation of the ITM at a fixed rotational speed in the print direction to transport the ink images toward a printing station where they are transferred to a substrate;
d. A detection system including a detection element positioned adjacent said ITM at a detection position upstream of said imaging station and downstream of said printing station by means of a rotating ITM, said detection system comprising said detection element and said detection element. a detection system configured to detect the foreign object by detecting an impact with the foreign object conveyed to the detection location;
e. A response operably coupled to the detection system for responding to detection of the foreign object by performing at least one anti-collision action to prevent potential collision between the foreign object and the printbar. a system;
printing system, including 21. The printing system of claim 20, wherein the detection system is configured to detect a foreign object conveyed to the detection location by mechanically detecting an impact between the sensing element and the foreign object. . A printing system in which a print bar of an imaging station forms ink images on a rotating intermediate transfer member (ITM), and the ink images are subsequently transported by the ITM to a print station where they are transferred to a substrate. A method of operating, said method comprising:
a. between the sensing element and a foreign object carried by the rotating ITM at a sensing position upstream of the imaging station and downstream of the printing station, during the time the sensing element is positioned adjacent to the ITM; detecting the foreign object by detecting an impact;
b. responding to the detection by performing at least one anti-collision action to prevent potential collision between the foreign object and the printbar;
A method, including 23. The method of claim 22, wherein detecting a foreign object carried by the rotating ITM is performed by mechanically detecting an impact between the sensing element and the foreign object. A printing system,
a. an intermediate transfer member (ITM) comprising a flexible endless belt mounted on a plurality of guide rollers;
b. An imaging station including a print bar disposed over the surface of the ITM, the print bar configured to form an ink image on the surface of the ITM by droplet deposition. and,
c. a conveyor for driving the rotation of the ITM at a fixed rotational speed in the print direction to transport the ink images toward a printing station where they are transferred to a substrate;
d. a detection system configured to detect foreign objects transported by a rotating ITM to a detection location upstream of said imaging station and downstream of said printing station;
e. A response operably coupled to the detection system for responding to detection of the foreign object by performing at least one anti-collision action to prevent potential collision between the foreign object and the printbar. a system;
A printing system comprising:
(i) the print bar includes an inkjet printhead; and (ii) the detection system and the response system determine whether performing the at least one anti-collision action is a future collision avoidance action between the foreign object and the inkjet printhead. A printing system configured to condition a calculated prediction of the intensity of a crash exceeding a predetermined threshold. A printing system in which a print bar containing an inkjet printhead forms ink images on a rotating intermediate transfer member (ITM) which is then transported by the ITM to a printing station where they are transferred to a substrate. A method of operating a
a. detecting a foreign object carried by the rotating ITM at a detection location upstream of an imaging station and downstream of the printing station;
b. Preventing a potential collision between the foreign object and the printbar provided that a calculated prediction of a future collision intensity between the foreign object and the inkjet printhead exceeds a predetermined threshold. responding to the detection by performing at least one anti-collision action for
A method, including A printing system,
a. an intermediate transfer member (ITM) comprising a flexible endless belt mounted on a plurality of guide rollers;
b. An imaging station including a print bar disposed over the surface of the ITM, the print bar configured to form an ink image on the surface of the ITM by droplet deposition. and,
c. a conveyor for driving the rotation of the ITM at a fixed rotational speed in the print direction to transport the ink images toward a printing station where they are transferred to a substrate;
d. a detection system configured to detect foreign objects transported by a rotating ITM to a detection location upstream of said imaging station and downstream of said printing station;
e. A response operably coupled to the detection system for responding to detection of the foreign object by performing at least one anti-collision action to prevent potential collision between the foreign object and the printbar. a system,
I. The response time to prevent potential collisions between the foreign object and the print bar depends on the speed of the rotating ITM and the imaging from the detected position along the path of travel of the ITM in the print direction. defined by the distance to the station and
II. The detection system and the response system are configured such that the at least one anti-collision action is performed within the response time, the response time being less than 1 second.
a response system;
printing system, including A print bar at an imaging station forms ink images on a rotating intermediate transfer member (ITM), said ink images being subsequently transferred in the print direction by said ITM to a print station where they are transferred to a substrate. A method of operating a transported printing system, the method comprising:
a. detecting a foreign object carried by the rotating ITM at a detection location upstream of an imaging station and downstream of the printing station;
b. responding to the detection by performing at least one anti-collision action to prevent potential collision between the foreign object and the printbar;
I. The response time to prevent potential collisions between the foreign object and the print bar depends on the speed of the rotating ITM and the imaging from the detected position along the path of travel of the ITM in the print direction. defined by the distance to the station and
II . the at least one anti-collision action is performed within the response time, the response time being less than 1 second;
and
A method, including A printing system,
a. an intermediate transfer member (ITM) comprising a flexible endless belt mounted on a plurality of guide rollers;
b. An imaging station including a print bar disposed over the surface of the ITM, the print bar configured to form an ink image on the surface of the ITM by droplet deposition. and,
c. a conveyor for driving the rotation of the ITM at a fixed rotational speed in the print direction to transport the ink images toward a printing station where they are transferred to a substrate;
d. a detection system configured to detect foreign objects transported by a rotating ITM to a detection location upstream of said imaging station and downstream of said printing station;
e. A response system including a printbar lift system operably coupled to the detection system for responding to detection of the foreign object, the response system detecting a potential collision between the foreign object and the printbar. a response system configured to respond to detection of the foreign object by prophylactically lifting the printbar;
printing system, including i. the print bars are positioned over the surface of the ITM with a minimum gap of G1 therebetween;
ii. wherein the response system is configured to respond to detection of the foreign object by raising the print bar to a height that is at least twice the height of the gap (G1);
29. The printing system of Claim 28. The response system responds such that the lift of the print bar is defined by the velocity of the rotating ITM and the distance from the detected position to the imaging station along the path of travel of the ITM in the print direction. 30. The printing system of any one of claims 28-29, configured to run in time. A printing system in which a print bar forms an ink image on a rotating intermediate transfer member (ITM), said ink images being subsequently transported by said ITM in the print direction to a printing station where they are transferred to a substrate. A method of operating a
a. detecting a foreign object carried by the rotating ITM at a detection location upstream of an imaging station and downstream of the printing station;
b. responding to the detection by performing at least one anti-collision action to prevent a potential collision between the foreign object and the print bar, wherein the at least one anti-collision action causes the printing including lifting the bar;
A method, including i. the print bars are positioned over the surface of the ITM with a minimum gap of G1 therebetween;
ii. the at least one anti-collision action includes lifting the print bar to a height that is at least twice the height of the gap (G1);
32. The method of claim 31. The print bar is positioned at an imaging station, and the lift of the print bar is responsive to detection of the foreign object to control the speed of the rotating ITM and the speed of movement of the ITM along the path of travel of the ITM in the print direction. 33. A method according to any one of claims 31 to 32, performed within a response time defined by the distance from the detection location to the imaging station.

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